While you are charting your bp, you might also note what is going on in your life. If you have a stressful event that will push up your bp. So things like work stress over a deadline, etc., family stress like a sick spouse/kid/pet, even things like a bad traffic day could push up your bp. Are you getting adequate sleep those weeks your bp is higher? Some research suggests increases in bp if you are fatigued. This is normal - people experience higher bp when they are stressed and upset. Its when your numbers are high and you are calm with no stresses that you have a problem.